Interrupted loop-cut alternative
The first thing i tend to teach people in 3d modeling is that loop cuts are good and that their geometries should be quad based.

Having told them that I immediately tell them that loop cuts arent ALWAYS a good thing and that not having them is sometimes preferential before they start to spam loops everywhere generating unnecessary geometry.

Its much more important that you have clean and simple topology than it is to work with loop cuts (unless you have a very good reason)

In your case I would finish the door and then model the lock as a separate object, keeping the geometry as simple as possible. If you parent the lock to the door (ctrl+p) it will stay with the door at all times when you move it.

Don't be afraid of non-manifold objects/meshes.
Unless you work in 3D printing, then be very afraid.